Yeah, there is an overlap between dex and magic as there is one between blessed and strength.
The dex/magic type weapons are quick strike and the blessed/strength weapons are more of a crushing nature.
Moon weapons are good if you have dex and magic and try to play it thief style, the mana regeneration aura of crescent weapons is more visible in PvE and even more in PvP. In PvP you may just as well not wear a thief ring at all.